Sir Thomas Mackenzie's great-grandson Bruce Richards and great-great-granddaughter Kiri Richards came to Queenstown from Nashville, Tennessee, to set out on a discovery of Sir Thomas' historical legacy.
They said the scenery on the Routeburn was breathtaking.
Sir Thomas, who died in 1930, was a keen explorer, who pushed for the construction of the Routeburn Track during his tenure as Minister of Tourism.
Cutting of the route by Harry Birley, of Glenorchy, began in 1912, the year Sir Thomas became prime minister of New Zealand.
Sir Thomas' name was used to commemorate Lake Mackenzie - a key landmark on the Routeburn Track.
Ultimate Hikes, which now includes the Routeburn in its guided walking portfolio, and hosted the pair, chose to continue the theme by naming its Mackenzie Lodge near Lake Mackenzie after him.
Mr Richards, a first-time tramper, learned about Sir Thomas when he was 9 years old and said it was a lifelong dream to walk in the footsteps of his great-grandfather.
"For so long, I've known this story about an ancestor who had created an iconic walking trail on the other side of the world.
"The fact that I've come here and done it and shared and enjoyed my experience with people from all over the world, in particular my daughter, has been just brilliant.
"I'm sure it is a great fulfilment of his legacy that so many people enjoy this amazing track.
"It's such an asset to the region," Mr Richards said.
The pair followed in a line of family members who had walked the Routeburn in honour of Sir Thomas - Mr Richards' mother and grandmother previously visited New Zealand and completed the track.
Father and daughter were delighted with the experience.
They also had advice for others walking the track.
"Take your time, take in the scenery. We were at the back of the walking group most of the time - not just because we were beginners, but to simply enjoy our surroundings."
